Elastic Cable Anchor with Deformable Ring for Bone Fixation
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Solution Overview
Problem
Existing methods for securely anchoring high-strength, polymeric cables to bony structures are inadequate due to their tendency to slip and failure under localized high compression, as they change diameter under tension and have low friction coefficients, making conventional gripping devices ineffective.
Innovation Solution
An anchoring fastener system comprising a deformable ring and an anchor post with a tapering transition, which compresses the ring between a collar and the substrate, creating a secure void to hold the cable, and can include a penetrating nail or screw with flutes for enhanced penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gripping devices are used to secure polymeric cables, then the cable can be anchored, but the cable slips due to low friction coefficient and changes diameter under tension
Solution Approach 1:
The invention changes the physical parameters of the gripping surface by using a deformable ring with a conical outside bevel that compresses the cable axially while the collar provides radial constraint. This transforms the cable compression into secure retention, changing the state of the cable from slippery to firmly held through controlled compression and friction.
Solution Approach 2:
The deformable ring acts as an intermediary element between the anchor post and the cable. It deforms under compression to create a secure grip on the cable while preventing direct high-pressure contact that would damage the cable. The ring mediates the force transmission and creates reliable retention through its deformation and the resulting friction.
2Reliability
If high pressure is applied to grip the cable locally, then the cable can be secured, but the cable fails by cutting
Solution Approach 1:
The invention segments the gripping function into two distinct components: the deformable ring that provides axial compression and the collar that provides radial constraint. This segmentation distributes the compressive force along the cable length rather than concentrating it at a single point, preventing local stress concentration that would cause cable cutting while maintaining secure retention.
Solution Approach 2:
The deformable ring serves as a protective intermediary between the anchor post and the cable. It absorbs and distributes the compressive forces, preventing direct high-pressure contact that would damage the cable. The ring deforms to create friction-based retention while shielding the cable from cutting forces.
3Reliability
If the cable is compressed to prevent slippage, then the cable can be secured, but the cable diameter changes under tension
Solution Approach 1:
The invention accepts and manages the cable's diameter change under tension by designing the collar and deformable ring to accommodate this variation. The collar's internal dimensions and the ring's deformability allow the cable to maintain its functional properties while still achieving secure retention through friction and compression, preventing slippage without requiring the cable to maintain a constant diameter.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively secures elastic cables by compressive forces and friction, preventing slippage and failure, allowing for stable fixation of fractures with known cable dimensions and properties.
Implementation Method 1
The system effectively secures elastic cables by compressive forces and friction, preventing slippage and failure
Implementation Method 2
The transition is dimensioned to compress the deformable ring between said lower throat of said collar and said tapering transition
Data Source
AI summary
An anchoring fastener is adapted for attaching an elastic cable to a substrate, and is suitable for use in stabilizing and fixating a bony fracture with an elastic cable having known diameter and elastic properties. The invention includes: a generally annular collar, a deformable centering ring seatable inside the annular collar, and an anchor post adapted to be passed through the annular collar and ring. A loop or bight of cable passed around a shoulder of the anchor post is retained under compression in a defined annular void defined between a shoulder of the post and a cylindrical bore in the annular collar.